The invention relates to an information recording apparatus with a disc loaded in a cassette which can be used mainly in the field of computing techniques as a background memory for smaller processors and terminals.
In the Hungarian Pat. No. 170,790 a cassette information recording apparatus is described that comprises a flexible circular disc provided with a solid centering hub which is loaded in a cassette. The magnetic disc is rotated at a predetermined speed and information is recorded on the rotating disc or information is read out therefrom. The information is recorded on concentric circular tracks of the disc. The apparatus comprises a drive unit, and the cassette can be inserted in the drive unit in which it takes a guided position, and the disc is rotated by a driving spindle driven by a motor located in the drive unit. In operation, the driving spindle is coupled to the hub of the flexible disc. A writing-reading head arranged in the drive unit can be inserted in the cassette to approach the information recording tracks through an opening defined in the base plate of the cassette.
The development of such a cassette information storage apparatus represented an advance compared to the conventionally used floppy and mini-floppy type of information storage equipment, because the rigid cassette provided a sufficient protection for the sensitive information recording disc. As is known, in floppy systems the flexible disc is protected by a comparatively thin cover of paper material, in which respective windows are made at both sides for receiving the recording head.
Owing to the introduction of the cassette technique which has information recording density values corresponding to those realisable in mini-floppy techniques, the volume of the drive unit was reduced and the storage and the handling of the information recording disc became easier. According to the Hungarian Pat. No. 170,790 an oblong-shaped cassette defines an oblong-shaped opening for the introduction of the head and this opening is arranged in the center line of the disc near to a side wall of the cassette. In the drive unit according to that patent a head moving arm supports a plurality of writing-reading heads, and the heads are moved in a radial direction parallel to the smaller side wall of the cassette.
With such an arrangement of the head receiving opening the width of the cassette is rather high compared to the diameter of the information recording disc, because the cassette should have a sufficient wall thickness beyond the outer side of the opening to ensure sufficient rigidity for the cassette. The lateral size of the drive unit was also rather great compared to the diameter of the disc, due to the requirement of the head movement in a lateral direction.
During operation the other side of the disc, which is opposite to the side coupled to the writing-reading head, should be pressed according to the required head pressure. When both sides of the disk in the cassettes are used for information recording, then the pressure is made by the insertion of a second writing-reading head. When only one side of the disc is used for information recording, the head pressure is established by the application of a pad made generally by an appropriate felt material. For the insertion of the second head or of the pad, the upper side of the cassette comprises a window arranged in a position corresponding to that of the opening for the head.
The second head or the pad is arranged in the drive unit and it is moved exactly in the same way as the first head. Owing to this construction also the height of the drive unit will be relatively great.
In the widely used conventional information recording equipment, in which only one side of the disc is used, the wear of the pad in the drive unit was rather great, and for that reason the replacement of the pad was often required. This made the readjustment of the drive unit necessary.
Although the cited construction using the cassette could provide a better protection for the flexible disc than the conventional paper covers could, both surfaces of the flexible information recording disc were exposed to mechanical damage through the windows of the cover. Apart from the hazard of such damage the cassette surface was exposed to the effects of dust and dirt which became serious through extended storage periods.
The above problems, which are connected with the presence of the exposed disc surfaces through the openings, with the guiding of the head movement and with the appropriate head support, are present in the conventionally used floppy technique, too.